In recent years the attention of comparative philologists has often concentrated on the problems presented by the IE semiconsonants. Brugmann established for IE two sets of sounds: vocalic [i, u, r, I, m, n\ and consonantal [i, u, r, /, m, n]. However, it was clear to Brugmann —and, indeed, to all his successors— that the two sets were -—at least in part-— in complementary distribution
